在對Hbase進行Scan的時候有時候會拋出ScannerTimeoutException，場景如下：
2012 15:28:52 (14mins, 41sec)
org.apache.hadoop.hbase.client.ScannerTimeoutException: 60622ms passed since the last invocation, timeout is currently set to 60000
at org.apache.hadoop.hbase.client.HTable$ClientScanner.next(HTable.java:1196)
at org.apache.hadoop.hbase.mapreduce.TableRecordReaderImpl.nextKeyValue(TableRecordReaderImpl.java:133)
at org.apache.hadoop.hbase.mapreduce.TableRecordReader.nextKeyValue(TableRecordReader.java:142)
at org.apache.hadoop.mapred.MapTask$NewTrackingRecordReader.nextKeyValue(MapTask.java:532)
at org.apache.hadoop.mapreduce.MapContext.nextKeyValue(MapContext.java:67)
at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:143)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:764)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)
at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1093)
at org.apache.hadoop.mapred.Child.main(Child.java:249)
原因查看步驟：
查找源碼如下：
long timeout = lastNext + scannerTimeout;
// If we are over the timeout, throw this exception to the client
// Else, it's because the region moved and we used the old id
// against the new region server; reset the scanner.
if (timeout < System.currentTimeMillis()) {
long elapsed = System.currentTimeMillis() - lastNext;
ScannerTimeoutException ex = new ScannerTimeoutException(
elapsed + "ms passed since the last invocation, " +
"timeout is currently set to " + scannerTimeout);
ex.initCause(e);
throw ex;
}
核實下如下代碼
long timeout = lastNext + scannerTimeout;
得出：ClientScanner.lastNext和HTable.scannerTimeout
跟蹤：HTable.scannerTimeout
this.scannerTimeout =
(int) conf.getLong(HConstants.HBASE_REGIONSERVER_LEASE_PERIOD_KEY, HConstants.DEFAULT_HBASE_REGIONSERVER_LEASE_PERIOD);
查看HConstants.HBASE_REGIONSERVER_LEASE_PERIOD_KEY和HConstants.DEFAULT_HBASE_REGIONSERVER_LEASE_PERIOD
我們可以得知如果沒有設置HConstants.HBASE_REGIONSERVER_LEASE_PERIOD_KEY那麽他們采用默認值即
public static long DEFAULT_HBASE_REGIONSERVER_LEASE_PERIOD = 60000;
跟蹤：ClientScanner.lastNext發現此為上次訪問時間
解決方案：
可以通過設置HConstants.HBASE_REGIONSERVER_LEASE_PERIOD_KEY解決
代碼如下：
config.setLong(HConstants.HBASE_REGIONSERVER_LEASE_PERIOD_KEY, 120000);